Enhancement mode III-nitride switch with increased efficiency and operating frequency

ABSTRACT

According to one exemplary embodiment, an efficient and high speed E-mode III-N/Schottky switch includes a silicon transistor coupled with a D-mode III-nitride device, where the silicon transistor causes the D-mode III-nitride device to operate in an enhancement mode. The E-mode III-N/Schottky switch further includes a Schottky diode coupled across the silicon transistor so as to improve efficiency, recovery time, and speed of the E-mode III-N/Schottky switch. An anode of the Schottky diode can be coupled to a source of the silicon transistor and a cathode of the Schottky diode can be coupled to a drain of the silicon transistor. The Schottky diode can be integrated with the silicon transistor. In one embodiment the III-nitride device is a GaN device.

The present application claims the benefit of and priority to a pendingprovisional patent application entitled “Power Factor Correction BoostCircuit using Enhanced Mode III-Nitride Power Device,” Ser. No.61/050,730 filed on May 6, 2008. The disclosure in that pendingprovisional application is hereby incorporated fully by reference intothe present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally in the field of switching circuits.More particularly, the invention is in the field of high voltageswitching circuits.

2. Background Art

High voltage circuits, such as power conversion circuits, typicallyrequire fast switches that are capable of handling high voltages withoutbreaking down. Conventionally, silicon devices, such as high voltagesilicon diodes and transistors, have been utilized to provide highvoltage switches. For example, a high voltage silicon field effecttransistor (FET), such as a high voltage metal oxide semiconductor FET(MOSFET), has been utilized as a high voltage switch in a power factorcorrection boost circuit.

When silicon devices, such as high voltage silicon diodes andtransistors, are utilized as switches in high voltage circuits, such aspower conversion circuits, they (i.e. the silicon devices) can store alarge amount of charge when conducting current. When the silicon devicesare turned off, the stored charge must be dissipated. However, the largeamount of charge stored by the silicon devices, such as high voltagesilicon diodes and transistors, can undesirably limit their efficiencyand operating frequency. Consequently, the efficiency and operatingfrequency of high voltage circuits, such as power conversion circuits,can be undesirably limited by the use of silicon devices, such as highvoltage silicon diodes and transistors, as high voltage switches.

SUMMARY OF THE INVENTION

Enhancement mode III-nitride switch with increased efficiency andoperating frequency, substantially as shown in and/or described inconnection with at least one of the figures, and as set forth morecompletely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a circuit diagram of a power factor correction boostcircuit in accordance with one embodiment of the present invention.

FIG. 2 illustrates a circuit diagram of an exemplary E-modeIII-nitride/Schottky switch in accordance with one embodiment of thepresent invention.

FIG. 3 illustrates a circuit diagram of a power factor correction boostcircuit in accordance with another embodiment of the present invention.

FIG. 4 illustrates a circuit diagram of an exemplary half-bridgeconfiguration utilizing exemplary E-mode III-nitride/Schottky switchesin accordance with one embodiment of the present invention.

FIG. 5 illustrates a circuit diagram of an exemplary full-bridgeconfiguration utilizing exemplary E-mode III-nitride/Schottky switchesin accordance with one embodiment of the present invention.

FIG. 6 illustrates a circuit diagram of an exemplary buck circuitutilizing exemplary E-mode III-nitride/Schottky switches in accordancewith one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an enhancement mode III-nitrideswitch with increased efficiency and operating frequency. The followingdescription contains specific information pertaining to theimplementation of the present invention. One skilled in the art willrecognize that the present invention may be implemented in a mannerdifferent from that specifically discussed in the present application.Moreover, some of the specific details of the invention are notdiscussed in order not to obscure the invention.

The drawings in the present application and their accompanying detaileddescription are directed to merely exemplary embodiments of theinvention. To maintain brevity, other embodiments of the presentinvention are not specifically described in the present application andare not specifically illustrated by the present drawings.

FIG. 1 shows a circuit diagram of an exemplary power factor correctionboost circuit coupled between an AC power source and a load inaccordance with one embodiment of the present invention. Power factorcorrection (PFC) boost circuit 100 is coupled between AC power source102, such as an AC line, and load 104 and includes full bridge rectifier106, capacitors 108 and 110, inductor 112, controller 114, enhancementmode (E-mode) group III-nitride switch 116 (also referred to simply as“E-mode III-N switch” 116 in the present application), “normally offswitch” 118, and resistors 120 and 122. E-mode III-N switch 116 includessilicon transistor 124 and depletion mode (D-mode) group III-nitridedevice 126 (also referred to simply as “D-mode III-nitride device” 126in the present application) and normally off switch 118 includesSchottky diode 128 and D-mode III-nitride device 130. Load 104 can be,for example, a resistive load, an inductive load, such as a step-downtransformer, or a capacitive load. Load 104 can be a load correspondingto a home appliance, such as a television set, for example.

As shown in FIG. 1, AC power source 102 is coupled to the inputs offull-bridge rectifier 106 at nodes 132 and 134, a first terminal ofcapacitor 108, which can be a filter capacitor, is coupled to a positiveoutput of full bridge rectifier 106 and a first terminal of inductor112, which can be a boost inductor, at node 136, and a second terminalof capacitor 108 is coupled to a negative output of full bridgerectifier 106 at node 138. Also shown in FIG. 1, a second terminal ofinductor 112 is coupled to a first terminal of E-mode III-N switch 116and a first terminal of normally off switch 118 at node 140 and a secondterminal of E-mode 111-N switch 116 is coupled to the negative output offull-bride rectifier 106 at node 138.

In E-mode III-N switch 116, silicon transistor 124 is coupled in serieswith D-mode III-nitride device 126, wherein the gate of D-modeIII-nitride device 126 is coupled to the source of silicon transistor124 and the drain of silicon transistor 124 is coupled to the source ofD-mode 111-nitride device 126. Silicon transistor 124 can be, forexample, a low voltage silicon transistor, such as a silicon FET. In oneembodiment, silicon transistor 124 can be a low voltage silicon MOSFET.D-mode III-nitride device 126 can comprise a group III nitridesemiconductor compound, such as aluminum nitride (AlN), indium nitride(InN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indiumgallium nitride (InGaN), or indium aluminum gallium nitride (InAlGaN).The aforementioned semiconductor compounds have a relatively wide directbandgap that permits highly energetic electronic transitions to occur.D-mode III-nitride device 126 is a high voltage device and has reducedcharge storage and a high mobility conduction channel, which enables it(i.e. D-mode III-nitride device 126) to conduct high current. As aresult of reduced charge storage, D-mode III-nitride device 126 providesincreased efficiency and increased operating frequency.

D-mode III-nitride device 126 is a normally on device. However, bycoupling silicon transistor 124 in series with D-mode III-nitride device126 as discussed above, silicon transistor 124 causes D-mode III-nitridedevice 126 to operate in an enhancement mode (E-mode). For example, whensilicon transistor 124 is turned on, D-mode III-nitride device 126 isalso turned on, thereby allowing current to flow through silicontransistor 124 and D-mode III-nitride device 126. When silicontransistor 124 is turned off, D-mode III-nitride device 126 turns off asa result of a voltage that develops across silicon transistor 124. Byincluding the series-coupled combination of silicon transistor 124 andD-mode III-nitride device 126, E-mode III-N switch 116 provides reducedcharge storage, thereby providing increased efficiency and increasedoperating frequency.

In normally off switch 118, Schottky diode 128 is coupled in series withD-mode III-nitride device 130. In particular, the anode of Schottkydiode 128 is coupled to the gate of D-mode III-nitride device 130 andthe cathode of Schottky diode 128 is coupled to the source of D-modeIII-nitride device 130. Schottky diode 128 can be a low voltage silicondiode in an embodiment of the present invention. D-mode III-nitridedevice 130, which is a high voltage device, can comprise similar groupIII nitride semiconductor compounds and provides similar advantages asD-mode III-nitride device 126. D-mode III-nitride device 130 is anormally on device. However, by coupling Schottky diode 128 in serieswith D-mode III-nitride device 130 as discussed above, Schottky diode128 causes D-mode III-nitride device 130 to turn off when it (i.e.Schottky diode 128) is in a reverse mode (i.e. when current flows fromcathode to anode).

For example, in a forward mode (i.e. when current flows from anode tocathode), Schottky diode 128 is turned on and D-mode III-nitride device130 is also turned on. The voltage drop across Schottky diode 128 in theforward mode has a negligible effect on D-mode III-nitride device 130,which is a high voltage device. In the reverse mode, D-mode III-nitridedevice 130 turns off as a result of a voltage that develops acrossSchottky diode 128. Thus, the combination of Schottky diode 128 andD-mode III-nitride device 130 can operate as a high voltage diode, wherethe anode of Schottky diode 128 can be an “anode” of the high voltagediode and the drain of D-mode III-nitride device 130 can be a “cathode”of the high voltage diode. By including the series-coupled combinationof Schottky diode 128 and D-mode III-nitride device 130, normally offswitch 118 provides reduced charge storage, thereby providing increasedefficiency and increased operating frequency.

Further shown in FIG. 1, a second terminal of normally off switch 118 iscoupled to first terminals of capacitor 110, which can be an outputcapacitor, resistor 120, and load 104, and second terminals of capacitor110 and load 104 can be coupled to the negative output of full-briderectifier 106 at node 138. Also shown in FIG. 1, a second terminal ofresistor 120 is coupled to a first terminal of resistor 122 and a firstinput (i.e. a feedback input) of controller 114 at node 144 and a secondterminal of resistor 122 is coupled to the negative output of full-briderectifier 106 at node 138. Resistors 120 and 122 form a voltage divider,which provides a feedback signal to the feedback input of controller 114at node at 144. Further shown in FIG. 1, an output of controller 114,which can be a PFC pulse width modulation (PWM) controller, is coupledto the gate of silicon transistor 124 and a second input of controller114 is coupled to the negative output of full-bridge rectifier 106 atnode 138. Controller 114 can be configured to control the on/off time ofE-mode III-N switch 116 by providing a pulse width modulated signal tothe gate of silicon transistor 124 to control the on/off time of silicontransistor 124.

During operation of PFC boost circuit 100, controller 114 provides a PWM(pulse width modulated) signal to the gate of silicon transistor 124 tocontrol the on/off time of E-mode III-N switch 116. When E-mode III-Nswitch 116 is turned on, current flows in a loop including E-mode III-Nswitch 116 and normally off switch 118, thereby causing charge to bestored in E-mode III-N switch 116 and normally off switch 118. WhenE-mode III-N switch 116 is turned off, the stored charge stored inE-mode III-N switch 116 and normally off switch 118 needs to bedissipated. This stored charge, however, is significantly less than thestored charge if, in place of switches 116 and 118, conventionalswitches were used—which resulted in significantly limiting theefficiency and operating frequency of, for example, a conventional PFCboost circuit.

In a conventional PFC boost circuit, a high voltage MOSFET is typicallyutilized in place of E-mode III-N switch 116 and a high voltage silicondiode is typically utilized in place of normally off switch 118.However, the high voltage MOSFET stores significantly more charge thanE-mode III-N switch 116 and the high voltage silicon diode storessignificantly more charge than normally off switch 118. Thus, byutilizing E-mode III-N switch 116 and normally off switch 118, anembodiment of the invention's PFC boost circuit 100 can significantlyreduce the amount of stored charge that needs to be dissipated comparedto a conventional PFC boost circuit. By reducing the amount of storedcharge that needs to be dissipated, E-mode III-N switch 116 and normallyoff switch 118 cause PFC boost circuit 100 to provide an increasedefficiency and an increased operating frequency compared to theconventional PFC boost circuit.

Also, by operating at a higher frequency, PFC boost circuit 100 canutilized smaller size passive components, such as capacitors andinductors, which can advantageously reduce the footprint of PFC boostcircuit 100, thereby advantageously reducing manufacturing cost.

FIG. 2 shows a circuit diagram of an exemplary E-modeIII-nitride/Schottky switch in accordance with one embodiment of thepresent invention. In one embodiment of the present invention, E-modeIII-nitride/Schottky switch 216 (also referred to simply as “E-modeIII-N/Schottky switch” 216 in the present application) can be utilizedin place of E-mode III-N switch 116 in FIG. 1. E-mode III-N/Schottkyswitch 216 includes silicon transistor 224, D-mode III-nitride device226, and Schottky diode 246. In FIG. 2, silicon transistor 224 andD-mode III-nitride device 226 correspond, respectively, to silicontransistor 124 and D-mode III-nitride device 126 in E-mode III-N switch116 in FIG. 1. Thus, silicon transistor 124 can be a low voltage siliconFET, such as a low voltage silicon MOSFET, and D-mode III-nitride device226 can comprise a group III nitride semiconductor compound, such asaluminum nitride (AlN), indium nitride (InN), gallium nitride (GaN),aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), orindium aluminum gallium nitride (InAlGaN).

As shown in FIG. 2, silicon transistor 224 is coupled with D-modeIII-nitride device 226 between nodes 238 and 240 and Schottky diode 246is coupled across silicon transistor 224. In particular, the anode ofSchottky diode 246 is coupled to the source of silicon transistor 224and the gate of D-mode III-nitride device 226 and the cathode ofSchottky diode 246 is coupled to the drain of silicon transistor 224 andthe source of D-mode III-nitride device 226. Schottky diode 246 can be alow voltage silicon Schottky diode in an embodiment of the presentinvention. In one embodiment, Schottky diode 246 can be integrated withsilicon transistor 224.

D-mode III-nitride device 226 is a normally on device. However, bycoupling silicon transistor 224 with D-mode III-nitride device 226 asdiscussed above, silicon transistor 224 causes D-mode III-nitride device226 to operate in an enhancement mode (E-mode). For example, whensilicon transistor 224 is turned on, D-mode III-nitride device 226 isalso turned on, thereby allowing current to flow through silicontransistor 224 and D-mode III-nitride device 226. When silicontransistor 224 is turned off, D-mode III-nitride device 226 turns off asa result of a voltage that develops across silicon transistor 224. Byincluding the combination of silicon transistor 224 and D-modeIII-nitride device 226, E-mode III-N/Schottky switch 216 providesreduced charge storage, thereby providing increased efficiency andincreased operating frequency.

Schottky diode 246 also provides reduced charge storage, which providesincreased efficiency and operating frequency. In addition, Schottkydiode 246 provides reduced reverse recovery time (i.e. a faster reverserecovery). Thus, an embodiment of the invention's E-mode III-N/Schottkyswitch 216 provides a high speed, high voltage switch having reducedcharge storage, which provides increased efficiency and operatingfrequency, and also provides a faster reverse recovery time. Thus,E-mode III-N/Schottky switch 216 can be advantageously utilized in highvoltage applications, such as power conversion applications, toadvantageously provide increased efficiency, increased operatingfrequency, and increased reverse recovery time compared to a highvoltage silicon FET, such as a high voltage silicon MOSFET.

FIG. 3 shows a circuit diagram of an exemplary power factor correctionboost circuit coupled between an AC power source and a load inaccordance with another embodiment of the present invention. PFCcorrection boost circuit 300 is substantially similar to PFC correctionboost circuit 100 in FIG. 1, with a difference being that E-modeIII-nitride/Schottky switch 316 (also referred to simply as “E-modeIII-N/Schottky switch” 316 in the present application) in PFC correctionboost circuit 300 is utilized in place of E-mode III-N switch 116 in PFCcorrection boost circuit 100. In FIG. 3, E-mode III-N/Schottky switch316 corresponds to E-mode III-N/Schottky switch 216 in FIG. 2. Byutilizing E-mode III-N/Schottky switch 316 between nodes 338 and 340 inplace of E-mode III-N switch 116, an embodiment of the invention's PFCcorrection boost circuit 300 provides similar advantages as PFCcorrection boost circuit 100, such as increased efficiency and increasedoperating frequency. Also, the increased reverse recovery time providedby E-mode III-N/Schottky switch 316 can increase the operating speed ofPFC correction boost circuit 300.

FIG. 4 shows a circuit diagram of a half-bridge configuration inaccordance with one embodiment of the present invention. Half-bridgeconfiguration 400 includes E-mode III-N/Schottky switches 416a and 416b,which are coupled between supply voltage 403, which is a DC supplyvoltage, and ground 405. Each of E-mode III-N/Schottky switches 416 aand 416 b correspond to E-mode III-N/Schottky switch 216 in FIG. 2.Half-bridge configuration 400 includes output terminal 407, which iscoupled to E-mode III-N/Schottky switches 416 a and 416 b at node 409.It is noted that half-bridge configuration 400 can also include othercomponents, such as a controller, which are known in the art but notshown in FIG. 4.

By utilizing E-mode III-N/Schottky switches 416 a and 416 b, anembodiment of the invention provides a half-bridge configuration thatadvantageously provides increased efficiency and operating frequency andfaster recovery time compared to a conventional half-bridgeconfiguration that utilizes switches comprising high voltage silicontransistors, such as high voltage MOSFETs.

FIG. 5 shows a circuit diagram of a full-bridge configuration inaccordance with one embodiment of the present invention. Full-bridgeconfiguration 500 includes E-mode III-N/Schottky switches 516 a, 516 b,516 c, and 516 c, which are coupled between supply voltage 503, which isa DC supply voltage, and ground 505. Each of E-mode III-N/Schottkyswitches 516 a, 516 b, 516 c, and 516 c correspond to E-modeIII-N/Schottky switch 216 in FIG. 2. Full-bridge configuration 500 alsoincludes inductor 507, which has a first terminal that is coupled toE-mode III-N/Schottky switches 516 a and 516 b at node 509 and a secondterminal that is coupled to E-mode III-N/Schottky switches 516 c and 516d at node 511. Full-bridge configuration 500 also has output terminal513, which is coupled to node 511. It is noted that full-bridgeconfiguration 500 can also include other components, such as acontroller, which are known in the art but not shown in FIG. 5.

By utilizing E-mode III-N/Schottky switches 516 a, 516 b, 516 c, and 516d, an embodiment of the invention provides a full-bridge configurationthat advantageously provides increased efficiency and operatingfrequency and faster recovery time compared to a conventionalfull-bridge configuration that utilizes switches comprising high voltagesilicon transistors, such as high voltage MOSFETs.

FIG. 6 shows a circuit diagram of a buck circuit in accordance with oneembodiment of the present invention. Buck circuit 600 includes E-modeIII-N/Schottky switches 616 a and 616 b, DC power supply 621, inputcapacitor 623, which is a filter capacitor, buck inductor 625, and buckcapacitor 627, which is also a filter capacitor. In buck circuit 600,each of E-mode III-N/Schottky switches 616 a and 616 b correspond toE-mode III-N/Schottky switch 216 in FIG. 2. Buck circuit 600 has outputterminals 629 and 631. Buck circuit 600 can also include a controller(not shown in FIG. 6) for controlling the on/off times of E-modeIII-N/Schottky switches 616 a and 616 b.

As shown in FIG. 6, input capacitor 623 is coupled across DC powersupply 621, E-mode III-N/Schottky switches 616 a and 616 b are coupledacross input capacitor 623, and buck inductor 625 and buck capacitor 627are coupled together across E-mode III-N/Schottky switch 616 b. Buckcircuit 600 can operate in a manner known in the art. By utilizingE-mode III-N/Schottky switches 616 a and 616 b, an embodiment of theinvention provides a buck circuit that advantageously provides increasedefficiency and operating frequency and faster recovery time compared toa conventional buck circuit that utilizes switches comprising highvoltage silicon transistors, such as high voltage MOSFETs.

As discussed above, in FIG. 1, an embodiment of the invention's PFCboost circuit includes an E-mode III-N switch, which includes a silicontransistor coupled to a D-mode III-nitride device, and a normally offswitch, which includes a Schottky diode coupled to a D-mode III-nitridedevice. As a result, the embodiment of the invention's PFC boost circuitprovides increased efficiency and increased operating frequency comparedto a conventional PFC boost circuit utilizing a high voltage silicontransistor, such as a high voltage MOSFET, and a high voltage silicondiode.

In FIG. 2, an embodiment of the invention's E-mode III-N/Schottky switchincludes a silicon transistor coupled with a D-mode III-nitride deviceand a Schottky diode coupled across the silicon transistor. As a result,the embodiment of the invention's E-mode III-N/Schottky switch providesincreased efficient and operating frequency and reduced reverse recoverytime compared to a high voltage switch comprising a high voltage silicontransistor, such as a high voltage MOSFET.

In FIGS. 3, 4, 5, and 6, the invention's E-mode III-N/Schottky switch isutilized in a PFC boost circuit, a half-bridge configuration, afull-bridge configuration, and a buck circuit, respectively, therebyadvantageously providing increased efficient and operating frequency andfaster recovery time.

From the above description of the invention it is manifest that varioustechniques can be used for implementing the concepts of the presentinvention without departing from its scope. Moreover, while theinvention has been described with specific reference to certainembodiments, a person of ordinary skill in the art would appreciate thatchanges can be made in form and detail without departing from the spiritand the scope of the invention. Thus, the described embodiments are tobe considered in all respects as illustrative and not restrictive. Itshould also be understood that the invention is not limited to theparticular embodiments described herein but is capable of manyrearrangements, modifications, and substitutions without departing fromthe scope of the invention.

1. An efficient and high speed E-mode III-N/Schottky switch comprising:a silicon transistor coupled with a D-mode III-nitride device, saidsilicon transistor causing said D-mode III-nitride device to operate inan enhancement mode; a Schottky diode coupled across said silicontransistor; said E-mode III-N/Schottky switch thereby achieving improvedspeed, efficiency, and reverse recovery time.
 2. The E-modeIII-N/Schottky switch of claim 1, wherein two of said E-modeIII-N/Schottky switches are coupled between a supply voltage and aground to form a half-bridge configuration.
 3. The E-mode III-N/Schottkyswitch of claim 1, wherein four of said E-mode III-N/Schottky switchesare coupled between a supply voltage and a ground to form a full-bridgeconfiguration.
 4. The E-mode III-N/Schottky switch of claim 3, wherein afirst and a second of said E-mode III-N/Schottky switches are coupledbetween said supply voltage and respective first and second terminals ofan inductor and a third and a fourth of said E-mode III-N/Schottkyswitches are coupled between said respective first and second terminalsof said inductor and said ground.
 5. The E-mode III-N/Schottky switch ofclaim 1, wherein a first said E-mode III-N/Schottky switch is coupledwith a second said E-mode III-N/Schottky switch across a DC power sourceto form a buck circuit.
 6. The E-mode III-N/Schottky switch of claim 5,wherein a buck inductor and a buck capacitor are coupled across saidfirst said E-mode III-N/Schottky switch.
 7. The E-mode III-N/Schottkyswitch of claim 1, wherein said silicon transistor is a low voltage FET.8. The E-mode III-N/Schottky switch of claim 1, wherein said D-modeIII-Nitride device is a GaN device.
 9. The E-mode III-N/Schottky switchof claim 1, wherein an anode of said Schottky diode is coupled to asource of said silicon transistor and a cathode of said Schottky diodeis coupled to a drain of said silicon transistor.
 10. The E-modeIII-N/Schottky switch of claim 1, wherein said Schottky diode isintegrated with said silicon transistor.
 11. A power factor correctionboost circuit having increased efficiency and operating frequency, saidpower factor correction boost circuit comprising: an E-mode III-N switchcoupled across positive and negative outputs of a full-bridge rectifier;a normally off switch coupled to said E-mode III-N switch; a controllerconfigured to control an on/off time of said E-mode III-N switch; saidE-mode III-N switch and said normally off switch each having reducedcharge storage, thereby causing said power factor correction boostcircuit to have said increased efficiency and operating frequency. 12.The power factor correction boost circuit of claim 11, wherein saidE-mode III-N switch comprises a silicon transistor coupled in serieswith a depletion mode III-nitride device, thereby causing said depletionmode III-nitride device to operate in an enhancement mode.
 13. The powerfactor correction boost circuit of claim 11, wherein said E-mode III-Nswitch comprises a silicon transistor coupled with a D-mode III-nitridedevice and a Schottky diode coupled across said silicon transistor,wherein said silicon transistor causes said D-mode III-nitride device tooperate in an enhancement mode.
 14. The power factor correction boostcircuit of claim 11, wherein said normally off switch comprises aSchottky diode coupled in series with a D-mode III-nitride device. 15.The power factor correction boost circuit of claim 11 further comprisinga boost inductor coupled between said positive output of saidfull-bridge rectifier and said E-mode III-N switch and said normally offswitch.
 16. The power factor correction boost circuit of claim 11further comprising an output capacitor coupled between said normally offswitch and said ground.
 17. The power factor correction boost circuit ofclaim 16 further comprising a voltage divider coupled across said outputcapacitor, wherein said voltage divider provides a feedback signal tosaid controller.
 18. The power factor correction boost circuit of claim12, wherein said D-mode III-nitride device is a GaN device and saidsilicon transistor is a low voltage FET.
 19. The power factor correctionboost circuit of claim 13, wherein said D-mode III-nitride device is aGaN device and said silicon transistor is a low voltage FET.
 20. Thepower factor correction boost circuit of claim 14, wherein saiddepletion mode III-nitride device is a GaN device.